EPOXI

Two intriguing investigations -- One flight-proven spacecraft

Science

EPOXI Science Overview

The Deep Impact flyby spacecraft has sufficient fuel to undertake further studies. The new mission, named EPOXI, is comprised of two projects with different scientific objectives.

DIXI, the Deep Impact Extended Investigation, continues the original Deep Impact theme of studying comets by flying past comet Hartley 2. A comparison of Hartley 2 with comets observed by other spacecraft missions in order to help determine which cometary features are primordial and which are the result of subsequent evolutionary processes will be a primary focus of the investigation.

EPOCh, Extrasolar Planet Observation and Characterization, used (Jan-Aug 2008) the Deep Impact high-resolution instrument (HRI) to observe stars with known transiting giant planets to characterize those planets and to search for others. This was accomplished by using the HRI as a photometer to measure the light coming from the star in frequent images (a typical rate of every 50 seconds) as the planet transits and is later eclipsed by the star. Characteristics of the light from the planet are measured when it is eclipsed by the star, and the presence of other planets may be detected by their transits or by gravitational effects on the position of the giant planet. Planets as small as three Earth masses may be detected in this way. EPOCh also observed the Earth in visible and infrared wavelengths to allow comparisons with future discoveries of Earth-like planets around other stars.